Periodic density functional calculations are carried out to investigate the structure and the stability of hydrated/hydroxylated TiO 2 layered compounds, nanosheets, and nanotubes. Due to a very efficient interlayer hydrogen bonding, the ABA-stacked "step 3" H 2Ti 30 7 compound is found to be the most stable bulk phase, in agreement with the experiment. For single sheets in a water-rich environment other forms are instead favored, all close in energy, namely, "step 2" titanates, hydroxylized-anatase-like layers, and lepidocrocite-TiO 2. Finally, it is shown that a lepidocrocite-TiO 2 sheet, when hydroxylated only on one side, spontaneously forms a scroll-like nanotube. The nanotube diameter estimated from our models perfectly matches the ∼3 nm value observed for the internal diameters of Na-free titania nanotubes.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physics and Astronomy(all)
- Density functional calculations
- Titanium dioxide